1. Field of the Invention
The present invention relates to an interior part of a vehicle.
2. Description of the Related Art
A temperature in a vehicle cabin becomes extremely high under the blazing sun in summer season. For example, in some cases, an air temperature in the vehicle cabin reaches nearly 70° C., and a surface temperature of an upper surface of an instrument panel reaches nearly 110° C.
Needless to say, it is unpleasant for occupants to ride in the vehicle under such a situation. In addition, even after the operation of ventilation or air-conditioning is started, a surface temperature of an interior part will not easily lowered, and radiation heat emanated over a long time greatly discomforts the occupants.
Further, the temperature increase of the interior part involves many problems in terms of design. For example, the interior part is generally composed of a material having a large coefficient of thermal expansion, such as resin or wooden board. Therefore, when the interior part is engaged with a vehicle body formed of a steel material with a small coefficient of thermal expansion, deformation of the part and interference thereof with the other parts occurs due to a discrepancy in the coefficients of thermal expansion. Hence, in order to prevent the deformation and interference of the parts, a use of expensive special parts, an improvement of design accuracy or an increase in the number of processes is required. This causes an increase in the cost of the interior parts.
In addition, a high quality material is required for the interior part in order to assure durability against discoloration at a high temperature and cracking due to repeated thermal expansion and contraction. As a consequence, an expensive material has been applied for the interior part.
Accordingly, various methods and technologies for restricting the increase of the surface temperature of the interior part have been proposed. Japanese Patent Application Laid-Open Nos. 2001-114149 and 2001-122044 disclose a method, in which an infrared reflective pigment is contained in the surface of the interior part.
Japanese Patent Translation Publication No. H8-507987 published in 1996 (PCT International Publication No. WO 94/14629) discloses a technology of diffusing heat to the entire part by extending a metal foil layer over an inner side of a skin from an upper region of the part, which receives direct rays, to a lower region thereof, which does not receive direct rays.